Method of measuring the performance of a prosthetic foot

ABSTRACT

A method of measuring the performance of a prosthetic foot includes obtaining a pressure distribution of the prosthetic foot during a motion of the prosthetic foot and determining whether the pressure distribution falls within a preselected range of performance values for the prosthetic foot. The pressure distribution comprises a trajectory illustrating the progression of a center of pressure of the prosthetic foot during motion. A prosthetic foot can also be designed to approximate a pressure distribution corresponding to a preselected range of performance values.

PRIORITY INFORMATION

This application claims priority to U.S. patent application Ser. No.______ filed Sep. 17, 2004, titled FOOT PROSTHESIS WITH RESILIENTMULTI-AXIAL ANKLE (Attorney Docket No. OSSUR.050A), a copy of which isincluded in Appendix B of this application, the entire contents of whichare hereby expressly incorporated by reference and should be considereda part of this specification.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present embodiments generally relate to prosthetic feet, and moreparticularly, to methods of measuring the performance of prostheticfeet.

2. Description of the Related Art

Methods for measuring the performance of prosthetic feet are known inthe art. Conventional methods include comparing the gait characteristicsof different prosthetic foot designs, as well as comparing the gaitcharacteristic of a prosthetic foot with the natural gait of a humanfoot. However, it is often difficult to illustrate the performance ofprosthetic foot designs based on said methods, or to provide a user witha simple and easy to understand performance comparison of prostheticfoot designs. Accordingly, a need exists for a simpler, easier tounderstand method for measuring and illustrating the performance of aprosthetic foot.

SUMMARY OF THE INVENTION

In accordance with one embodiment disclosed herein, a method ofmeasuring the performance of a prosthetic foot is provided. The methodcomprises the steps of obtaining a pressure distribution of a prostheticfoot measured as the foot is in motion and determining whether thepressure distribution falls within a preselected range of performancevalues for the prosthetic foot.

In accordance with another embodiment, a method for designing aprosthetic foot is provided. The method comprises obtaining a pressuredistribution of at least a portion of a prosthetic foot that is inmotion and designing the prosthetic foot to approximate a desiredpressure distribution corresponding to a preselected range of rolloverperformance values.

In accordance with still another embodiment, a method for illustratingthe performance of a prosthetic foot is provided. The method comprisesobtaining a pressure distribution of a prosthetic foot while it's inmotion and displaying the pressure distribution on an image of theprosthetic foot to demonstrate the performance of the foot.

In yet another embodiment, a method of comparing the performance ofprosthetic feet is provided. The method comprises obtaining a pressuredistribution of a first prosthetic foot, where the pressure distributiondefines a first trajectory. The method also comprises obtaining apressure distribution of a second prosthetic foot, where the pressuredistribution defines a second trajectory. The method also comprisescomparing the first and second trajectories and determining which ofsaid first and second prosthetic feet has a superior performance basedon said comparison.

In still another embodiment, a method of comparing the performance of aprosthetic foot and a human foot is provided. The method comprisesobtaining a pressure distribution of a human foot, the pressuredistribution defining a first trajectory. The method additionallycomprises obtaining a pressure distribution of a prosthetic foot, thepressure distribution defining a second trajectory. The method alsocomprises comparing the first and second trajectories and determining aperformance rating for the prosthetic foot based on said comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a system for measuring the performance of aprosthetic foot.

FIG. 2 is a side view of a prosthetic foot moving over a surface used tomeasure the performance of the prosthetic foot.

FIG. 3 is an image of a prosthetic foot and a pressure distribution ofthe foot.

FIG. 4 is another image of a prosthetic foot.

FIG. 5 is an image of two prosthetic foot designs and theircorresponding pressure distributions.

FIG. 6 is an image of a prosthetic foot and a human foot, and theircorresponding pressure distributions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a system 100 for measuring the performance of aprosthetic foot or other leg support device. In one embodiment, thesystem 100 can be used to measure the performance of an orthotic devicedisposed on a human foot, such as a foot or ankle brace. In stillanother embodiment, the system 100 can be used to measure theperformance of a prosthetic knee. Accordingly, the scope of theinvention herein disclosed should not be limited by the particulardisclosed embodiments described below. Moreover, the embodiments beloware not limited to prosthetic feet but can be applied to other legsupport devices, including orthotic devices.

As shown in FIG. 1, The system 100 preferably comprises a surface 10,wherein the surface 10 includes a plurality of sensors 12 configured tosense a force exerted thereon by the prosthetic foot. The sensors 12communicate with a computer 20, which obtains the sensed forces from thesensors 12. In one preferred system, the surface 10 comprises afootscan® plate and the computer 20 comprises a footscan® 3D box, bothby RS Scan International of Belgium. However, the system 100 cancomprise any combination of components capable of obtaining the pressuredistribution of a prosthetic foot or other leg support device, asdiscussed below. Another such system is disclosed in U.S. Pat. No.6,505,522, issued on Jan. 14, 2003 to Wilssens, the contents of whichare hereby incorporated by reference in their entirety and should beconsidered a part of this specification.

In a preferred embodiment, the surface 10 comprises a plank 10 uponwhich a prosthetic foot 200 is placed to obtain the pressuredistribution of the prosthetic foot 200, as shown in FIG. 2. In theillustrated embodiment, the prosthetic foot 200 is an Elation™ foot byÖssur of Iceland. Preferably, the prosthetic foot 200 is moved over theplank 10 to obtain the pressure distribution while the prosthetic foot200 is in motion. For example, a user wearing the prosthetic foot 200can move over the plank 10 in a posterior-anterior fashion between aheel-strike and a toe-off position of the prosthetic foot 200. As usedherein, posterior refers to the rear portion or back of the prostheticfoot 200 and anterior refers to the forward portion of front of theprosthetic foot 200. The posterior-anterior motion of the prostheticfoot 200 during use is also known as the rollover of the prosthetic foot200.

Continuing with FIG. 2, in one embodiment the user can move over theplank 10 using a substantially normal walking stride. In anotherembodiment, the user can move over the plank 10 using a running orjogging stride. In the illustrated embodiment, the prosthetic foot 200is shown during a toe-off position on the plank 10. One of ordinaryskill in the art will recognize that the prosthetic foot 200 illustratedin FIG. 2 depicts one prosthetic foot design and that the embodimentsdisclosed herein are not limited to the prosthetic foot designsdisclosed.

With reference to FIGS. 1-3, the computer 20 preferably collects theforce data from the sensors 12 and calculates a corresponding pressureexerted by the prosthetic foot 200 at each of the sensors 12 via asuitable software program. The pressure corresponds to the force exertedby the prosthetic foot 200 on one of the sensors 12 over an area of thefoot 200 disposed over said sensor 12. Accordingly, the center ofpressure corresponds to a geometric indication of the pressure exertedover said area. For example, where the prosthetic foot 200 exerts auniform force over the area disposed on the sensor 12, the center ofpressure would be the geometric center of the area. However, where theexerted force is greater on a first portion of the area than a secondportion of the area, the center of pressure would instead be disposedcloser to said first portion, not at the geometric center of the area.The center of pressure values obtained during the motion of theprosthetic foot 200 over the surface 10 collectively define a pressuredistribution of the foot.

In one embodiment, the computer 20 preferably generates an image of thepressure distribution using said software. In one embodiment, the imageis a static image, such as a photograph. In another embodiment, theimage is a dynamic image showing the progression of the center ofpressure of the prosthetic foot 200 as the prosthetic foot 200 movesover the surface 10.

As shown in FIG. 3, the pressure distribution comprises a trajectory ofthe center of pressure of the prosthetic foot 200 during theposterior-anterior motion or rollover of the prosthetic foot 200. In oneembodiment the computer 20 displays the pressure distribution andincludes an image of the prosthetic foot 200, such as an image of a sole210 of the prosthetic foot 200, as shown in FIG. 3. In the illustratedembodiment, the prosthetic foot 200 is a left foot model of the LPVari-Flex® by Össur, as described in U.S. patent application Ser. No.10/642,125, filed Aug. 15, 2003, which is hereby incorporated byreference in its entirety and should be considered a part of thisspecification. However, as discussed above, an image of the right footmodel, and its associated pressure distribution, can also be displayed,as desired by the user. In another embodiment, the force or pressuredistribution data collected by the computer 20 can be transferred to aseparate device and used to generate the image of the pressuredistribution and/or prosthetic foot 200.

As shown in FIG. 3, in one embodiment the image of the sole 210 alsoillustrates the degree of pressure exerted by the prosthetic foot 200 atdifferent locations of the sole 210 during the posterior-anteriormotion. For example, the pressure level can be illustrated using aspectrum of color with areas of lower pressure indicated with one shadeor pattern, and areas of a higher pressure indicated with another shadeor pattern. In the illustrated embodiment, a lower pressure isillustrated by a lighter color, such as green, along a periphery 222 ofa posterior end 220 of the prosthetic foot 200. In contrast, a higherpressure is illustrated by a darker color, such as a red, at a centralportion 224 of the posterior end 220. Likewise, in the illustratedembodiment, areas of lower pressure are shown at a periphery 232 of ananterior end 230 of the prosthetic foot 200, whereas areas of higherpressure are illustrated at a central portion 234 of the anterior end230. Though the image of the prosthetic foot 200 in FIG. 3 uses thecolors green, red and yellow to illustrate areas of different pressure,any color shade or pattern can be used to illustrate said pressuresdifferences.

As one of ordinary skill in the art will recognize, measurement of thepressure distribution of the prosthetic foot 200 is not limited to theuse of the system 100 described above and shown in FIG. 1. In anotherembodiment, the pressure distribution can be obtained from sensors (notshown) disposed on the prosthetic foot 200. In one embodiment, saidsensors are configured to communicate a force exerted by the prostheticfoot 200 during motion to a central processing unit (not shown). Thepressure distribution can then be generated as described above. Inanother embodiment, said sensors collect said pressure distributiondata, which may later be used to generate an image of the pressuredistribution of the prosthetic foot 200. The sensors 12 can comprise anysuitable structure configured to sense a force applied by the prostheticfoot 200 during motion. For example, in one embodiment the sensors 12can comprise sensing strips or sensing areas.

In the embodiment illustrated in FIG. 3, the pressure distributioncomprises a plurality of dots 300, or pressure points, extending betweenthe posterior end 220 and the anterior end 230 of the prosthetic foot200. In one embodiment, the posterior end 220 corresponds to a heelsection of the prosthetic foot 200 and the anterior end 230 correspondsto a toe section of the prosthetic foot 200.

With reference to FIGS. 1 and 3, each of the plurality of dots 300,which together define the pressure distribution, corresponds to a forcereading sensed by the sensors 12 (i.e., a pressure point). Accordingly,each of the dots 300 corresponds to a reading of the sensors 12.Additionally, the pressure distribution illustrates the performance ofthe prosthetic foot 200. In one embodiment, the performance is definedby the spacing between the dots 300, which represents the general speedof the posterior-anterior motion or rollover of the prosthetic foot 200.As illustrated in FIG. 3, the dots 300 are generally close to each otherin a first portion 310 of the pressure distribution of the foot 200,which represents a slower posterior-anterior motion or rollover of theprosthetic foot 200 in the first portion 310. In contrast, the dots 300are generally further apart in a second portion 320 of the pressuredistribution, which represents a faster rollover of the prosthetic foot200 in the second portion 320.

One of ordinary skill in the art will recognize that the number of dots300 in the pressure distribution for the prosthetic foot 200, e.g. inFIG. 3, depends on the measurement frequency of the system 100 and theamount of time the prosthetic foot 200 is in contact with the surface10. For example, if the measurement frequency of the system 100 isapproximately 120 Hz, and the average contact time for the prostheticfoot 200 during a walking motion is between about 0.65 and about 0.75seconds, then the pressure distribution would include between aboutseventy-eight and about ninety pressure points or dots 300. In contrast,if the measurement frequency of the system 100 is approximately 350 Hzand the average contact time for the prosthetic foot 200 remains thesame, the pressure distribution would include between about 227 andabout 262 dots 300. Preferably, the measurement frequency of the system100 if between about 20 and about 1000 Hz. More preferably, themeasurement frequency of the system 100 is between about 50 and about500 Hz.

With continuing reference to FIG. 3, the spacing between the dots 300can also illustrate how smooth the rollover of the prosthetic foot 200is. Preferably, for substantial rollover smoothness, the dots 300 at theposterior end 220, or heel section of the foot 200, are generally closetogether, illustrating the absorption of energy during heel strike. Thedots 300 then preferably grow generally further apart as the prostheticfoot 200 moves anteriorly, illustrating a more rapid posterior-anteriormotion of the prosthetic foot 200 and energy return at toe-off. In oneembodiment, the dots 300 at the energy return stage are between about10% to about 200% further apart than at the energy absorption stage. Inanother embodiment, the dots 300 are between about 50% and about 100%further apart than at the energy absorption stage. In still anotherembodiment, the dots 300 are between about 10% and about 50% furtherapart than at the energy absorption stage. Preferably, over the entirerollover of the foot 200, the spacing between substantially every set oftwo dots does not vary by more than between about 10% and about 300%,and more preferably between about 50% and about 200%, from the spacingbetween another set of two dots. In another embodiment, the spacingbetween substantially every set of two dots does not vary by more thanbetween about 10% and about 200% from an average spacing between thedots 300, over the entire rollover of the prosthetic foot 200. Asubstantially smooth rollover allows for sufficient compression of theposterior end 220 to store energy, which will be returned during toe-offat the anterior end 230 of the prosthetic foot 200. Said storage andreturn of energy may vary between different prosthetic foot designs, aswell as between users.

With continuing reference to FIG. 3, the spacing between the dots 300can also illustrate the degree of dorsi-flexion and plantar flexion ofthe prosthetic foot 200 during rollover. For example, if the prostheticfoot 200 provides significant resistance to rollover duringdorsi-flexion, the dots 300 will appear substantially concentrated andmay in some cases be shown to move posteriorly before moving anteriorly.Likewise, the more significant the resistance to rollover is duringplantar flexion of the prosthetic foot 200, the generally closer thedots 300 are, which may even move posteriorly as described above,illustrating an interruption in the progression of rollover. Asillustrated in FIG. 5 with respect to a metatarsal or forefoot region240 of the prosthetic foot 200, such a resistance or interruption inrollover is exhibited as a discontinuity or kink 330 in the trajectoryof the pressure distribution. Such significant resistance to rollovercan result in added strain on a user's knee, creating a hyper-extensionmomentum on the knee and requiring the user to exert additional muscleforce to complete the rollover of the foot 200. On the other hand, verylittle resistance to rollover when the forefoot region 240 touches thesurface 10, which is exhibited by relatively larger spacing between thedots 300, may result in buckling of the knee, creating a flexion momenton the knee. Thus, in one embodiment, this system can be used to designa foot without such kinks 330 (e.g., substantially every dot is disposedanterior to the previous dot), or large spacing between the dots 300.

In another embodiment, the performance of the prosthetic foot 200 isillustrated by the frequency of the dots 300. For example, if thepressure distribution has very few dots 300, the rollover of theprosthetic foot 200 is generally fast. In contrast, if the pressuredistribution has many dots 300, the rollover of the prosthetic foot 200is generally slow.

In still another embodiment, illustrated in FIG. 4, the performance ofthe prosthetic foot 200 is defined by the trajectory of the pressuredistribution during the rollover of the prosthetic foot 200. Theprosthetic foot 200 is a right foot model, as described in U.S.Provisional Patent Application No. 60/575,142. Preferably, thetrajectory of the center of pressure starts generally at the center ofthe posterior end 220 or heel and travels in a substantially straightline through a mid-section 250 of the foot 200 until it reaches theforefoot region 240 of the foot 200. The trajectory then preferablycurves medially, or toward an inner (or medial) edge 260 of theprosthetic foot 200 and away from an outer (or lateral) edge 270 of thefoot 200. The trajectory preferably continues generally toward theanterior end 230 of the prosthetic foot 200. In the illustratedembodiment, where the prosthetic foot 200 is a right foot model, theinner edge 260 of the foot 200 is the left-hand side edge, so that amedial progression of the pressure distribution corresponds to atrajectory that curves left. The lateral portion of the foot 200 is onthe outer edge 270 of the foot 200 and corresponds to the right-handside edge in a right foot model. Similarly, in an embodiment where theprosthetic foot 200 is a left foot model, the inner edge 260 is theright-hand side edge of the foot 200 and the outer edge 270 is theleft-hand side edge. Accordingly, for a left foot model, medialprogression of the pressure distribution corresponds to a trajectorythat curves right. In one embodiment, the trajectory of the pressuredistribution curves medially and continues toward a toe section 280 ofthe anterior end 230, corresponding generally to the location of a firstand second toes on a human foot.

With reference to FIGS. 3 and 4, a reference line 290 may be used toillustrate the degree of medial-lateral motion of the pressuredistribution as the foot 200 moves from the posterior end 220 to theanterior end 230. In one embodiment, the reference line 290 can bealigned, e.g., by a user operating the computer 20, along a longitudinalcenter of the foot 200 so that generally equal areas of the foot 200 areon either side of the reference line 290. In said embodiment, thereference line 290 thus represents an axis of the foot 200. The degreeof medial-lateral motion of the foot 200 during rollover can thereforebe more easily recognized and measured (e.g., via the deviation of thepressure distribution from the reference line 290). In FIG. 3, thepressure distribution has a trajectory that is substantially linear andgenerally coincides with the reference line 290, which illustrates thelack of medial-lateral motion of the foot 200 during rollover. However,in another embodiment the reference line 290 need not be aligned withthe longitudinal center of the foot 200, as shown in FIG. 4. Here, thereference line 290 extends from the posterior end 220 toward the inneredge 260 of the foot 200, but the medial-lateral movement of thepressure distribution is readily recognizable.

The performance of the prosthetic foot 200 can be measured by comparingthe pressure distribution of the prosthetic foot 200 to a desiredrollover performance. In one embodiment, the desired rolloverperformance comprises a preselected range of performance values for theprosthetic foot 200. For example, the preselected range can consist orvalues for the speed of the rollover of the prosthetic foot 200, thedegree of curvature for the trajectory of the pressure distribution(e.g., the degree of media-lateral motion), and the smoothness of therollover as defined by the spacing of the dots 300 and the lack of anykinks 330 (see FIG. 5). In another embodiment, the preselected range canconsist of performance values corresponding to the rollover profile of ahuman foot. However, the desired rollover performance can comprise othercharacteristics generally used in measuring the performance of aprosthesis.

In one embodiment, the pressure distribution data obtained can be usedto design or redesign the prosthetic foot 200. For example, the designof the prosthetic foot 200 can be modified to approximate a desiredpressure distribution or rollover profile. In one embodiment, theprosthetic foot 200 can be designed or redesigned to provide a generallystraight rollover trajectory, as shown in FIG. 3. In another embodiment,the prosthetic foot 200 can be designed to provide a prosthetic foot 200whose rollover trajectory curves first laterally and then furthermedially as the foot 200 moves anteriorly, as shown in FIG. 5. Inanother embodiment, the prosthetic foot 200 can be designed to provideslower rollover during heel-strike and toe-off. In still anotherembodiment, the prosthetic foot 200 can be designed to provide fasterrollover in between heel-strike and toe-off. In yet another embodiment,the pressure distribution data obtained can be used to design theprosthetic foot 200 to provide a rollover profile that approximates therollover profile of a human foot (see FIG. 6). In another embodiment,the degree of pressure exerted by the prosthetic foot 200, asillustrated by the color shades of an image of the prosthetic foot 200,can be used to design the prosthetic foot 200 to increase or lessen thedegree of pressure exerted at a location of the sole 210 of theprosthetic foot 200, such as at the posterior end 220, the anterior end230, the forefoot 240 or the mid section 250 of the foot 200. In stillanother embodiment, the pressure distribution data can be used to designor redesign the prosthetic foot 200 to provide a more fluid rolloverbetween heel-strike and toe-off. Further discussion of features used inthe design of a prosthetic foot to achieve a fluid rollover can be foundin U.S. patent application Ser. No. 10/642,125, filed Aug. 15, 2003,which is hereby incorporated by reference in its entirety and should beconsidered a part of this specification.

The prosthetic foot 200 can be designed in any suitable way to achievethe desired preselected range of rollover performance values. In oneembodiment, a sole 210 of the prosthetic foot 200 can be designed toachieve the desired rollover. For example, the prosthetic foot 200 canemploy different materials of selected stiffness at preselectedlocations on the prosthetic foot 200, wherein said materials areselected to guide the rollover of the prosthetic foot 200 in a desiredmanner, such as to achieve a more medial-lateral progression of thecenter of pressure of the prosthetic foot 200. In another embodiment,the prosthetic foot 200 can comprise a foot cover (not shown), whereinthe foot cover is designed to include different materials of differentstiffness at preselected locations to guide the rollover of the foot200. Further discussion of such foot cover designs and features used inthe design of prosthetic feet to achieve a desired rollover performancecan be found in U.S. Provisional Patent Application No. 60/575,587,filed May 28, 2004, which is hereby incorporated by reference in itsentirety and should be considered a part of this specification.

As discussed above, the pressure distribution of the prosthetic foot 200can be displayed to illustrate the performance of the prosthetic foot200 during the posterior-anterior motion or rollover of the foot 200. Ina preferred embodiment, the pressure distribution is displayed on animage of the prosthetic foot 200, as shown in FIG. 3. In one embodiment,the image of the prosthetic foot 200 includes an image of the sole 210of the prosthetic foot 200.

In another embodiment, the pressure distribution of a second prostheticfoot 200′ is also illustrated and compared to the pressure distributionof the prosthetic foot 200, as shown in FIG. 5. Preferably, the pressuredistribution of the second prosthetic foot 200′ is displayed on an imageof the second prosthetic foot 200′. In another embodiment, the pressuredistribution of the second prosthetic foot 200′ can be displayedtogether with the pressure distribution of the prosthetic foot 200. Inthe illustrated embodiment, two right foot models of the prosthetic feet200, 200′ are compared; the prosthetic foot 200 is a Talux® foot byÖssur and the prosthetic foot 200′ is a Luxon Max model by Otto Bock ofMinneapolis, Minn. Alternatively, two left foot models, or one left footmodel and one right foot model, can be compared. As illustrated in FIG.5, the prosthetic foot 200′ exhibits a more uniform distribution of dots300 without any kinks, as discussed above.

In still another embodiment, the pressure distribution of a prostheticfoot 200 is compared to a pressure distribution of a human foot 400, asshown in FIG. 6. Preferably, the pressure distribution of the human foot400 is displayed on an image of the human foot 400. In anotherembodiment, the pressure distribution of the human foot 400 can bedisplayed together with the pressure distribution of the prosthetic foot200. In the illustrated embodiment, the image of the human foot 400(seen on the left hand side in FIG. 6) is that of a left foot, whereasthe image of the prosthetic foot 200 (seen on the right hand side inFIG. 6) is that of a right foot model of the foot design described inU.S. Provisional Patent Application No. 60/575,142. Alternatively, thehuman foot 400 can be a right foot and the prosthetic foot 200 can be aleft foot model, or both can be right feet or left feet.

The pressure distributions generated as discussed above can be used tocompare the performance of different prosthetic foot designs 200, 200′,as shown in FIG. 5. Said comparison can be used in advertisements orother publications to illustrate the difference in performance betweenthe prosthetic foot designs 200, 200′. For example, the pressuredistribution trajectory for each of the designs 200, 200′ can begenerated or obtained and compared with each other, as shown in FIG. 5.In one embodiment, said comparison can be displayed as discussed aboveto illustrate the difference in performance of the prosthetic footdesigns 200, 200′ relative to each other. A user can then determine,based on said comparison, which of the designs 200, 200′ has a superiorperformance. For example, the user can compare the pressure distributiontrajectories for the prosthetic foot designs 200, 200′ to determinewhich design has the better medial-lateral motion. Additionally, theuser can compare the distance or spacing between the dots 300, 300′, orpressure points, of the pressure distribution trajectories for theprosthetic foot designs 200, 200′ to determine which design provides thesmoother rollover. Also, the user can compare the frequency of the dots300, 300′ of the pressure trajectories for the prosthetic foot designs200, 200′ to determine which design has the faster rollover.

In another embodiment, the pressure distribution generated as discussedabove can be used to compare the performance of a prosthetic footrelative to a human foot. For example, the pressure distributiontrajectory for the prosthetic foot 200 can be generated or obtained andcompared with the pressure distribution for the human foot 400, as shownin FIG. 6. In one embodiment, said comparison can be displayed asdiscussed above to illustrate the performance of the prosthetic foot 200relative to the human foot 400. A user can then determine, based on saidcomparison, the performance of the prosthetic foot 200 relative to thehuman foot 400. For example, the user can determine how closely themedial-lateral motion of the prosthetic foot 200 approximates themedial-lateral motion of the human foot 400. Additionally, the user candetermine how closely the posterior-anterior motion of the prostheticfoot 200 approximates the posterior-anterior motion of the human foot400. Also, the user can compare the smoothness or quickness of therollover in the manner discussed above. Additionally, the prostheticfoot 200 could be assigned a performance rating based on the performanceof the prosthetic foot 200 relative to the rollover profile of the humanfoot 400.

All of these aspects are intended to be within the scope of theinvention herein disclosed. These and other aspects of the presentinvention will become readily apparent to those skilled in the art fromthe appended claims and from the preceding detailed description of thepreferred embodiments having reference to the attached figures, theinvention not being limited to any particular preferred embodiment(s)disclosed.

1. A method of measuring the performance of a prosthetic foot,comprising: obtaining a pressure distribution of a prosthetic footmeasured as the foot is in motion; and determining whether the pressuredistribution falls within a preselected range of performance values forthe prosthetic foot.
 2. The method of claim 1, wherein the pressuredistribution is measured via a surface incorporating a plurality ofsensors, wherein the prosthetic foot moves over the surface, saidsensors sensing a force exerted by at least a portion of the prostheticfoot on the surface, the sensors communicating said sensed force to acomputer.
 3. The method of claim 1, wherein the desired range ofperformance includes a desired range of anterior-posterior motion. 4.The method of claim 1, wherein the desired range of performance includesa desired range of medial-lateral motion.
 5. The method of claim 1,wherein said desired range of performance is defined by the frequency ofpressure points in the pressure distribution.
 6. The method of claim 1,wherein said desired range of performance is defined by the spacing ofpressure points in the pressure distribution.
 7. The method of claim 1,wherein said desired range of performance is defined by the smoothnessof a trajectory of the pressure distribution.
 8. The method of claim 1,further comprising displaying the pressure distribution.
 9. The methodof claim 8, wherein said display includes an image of a sole portion ofthe prosthetic foot.
 10. The method of claim 8, wherein the displaycomprises a trajectory of a center of pressure of the prosthetic footduring said motion.
 11. The method of claim 10, wherein said trajectorycorresponds to a rollover profile of the prosthetic foot between aheel-strike position and a toe-off position of said motion.
 12. A methodfor designing a prosthetic foot, comprising: obtaining a pressuredistribution of at least a portion of a prosthetic foot in motion; anddesigning the prosthetic foot to approximate a desired pressuredistribution corresponding to a preselected range of rolloverperformance values for the prosthetic foot.
 13. The method of claim 12,wherein modifying the design of at least one portion of the prostheticfoot comprises redesigning a sole of the prosthetic foot.
 14. The methodof claim 12, wherein the prosthetic foot comprises a foot cover andwherein modifying the design of the prosthetic foot comprisesredesigning the foot cover.
 15. The method of claim 12, whereinmodifying the design comprises incorporating materials of selectedstiffness in the prosthetic foot.
 16. The method of claim 12, whereinmeasuring the pressure comprises generating a center of pressureprofile.
 17. The method of claim 12, wherein the preselected range ofrollover performance values substantially approximates the rollover of ahuman foot.
 18. A method of illustrating the performance of a prostheticfoot, comprising: obtaining a pressure distribution of a prosthetic footduring motion of the foot; and displaying the pressure distribution onan image of the prosthetic foot to demonstrate a rollover performance ofthe foot.
 19. The method of claim 18, wherein the image of theprosthetic foot includes an image of a sole of the prosthetic foot. 20.The method of claim 18, further comprising displaying a pressuredistribution of a second prosthetic foot.
 21. The method of claim 20,wherein the pressure distribution of the second prosthetic foot isdisplayed on an image of the second prosthetic foot.
 22. The method ofclaim 18, further comprising displaying a pressure distribution of ahuman foot.
 23. The method of claim 22, wherein the pressuredistribution of the human foot is displayed on an image of the humanfoot.
 24. The method of claim 18, wherein the motion of the footincludes a posterior-anterior motion.
 25. The method of claim 18,wherein displaying the pressure distribution includes a trajectory ofthe pressure distribution, wherein the smoothness of the trajectorydemonstrates the performance of the prosthetic foot.
 26. The method ofclaim 18, wherein displaying the pressure distribution includes aplurality of pressure points, wherein the frequency of the pressurepoints demonstrates the performance of the prosthetic foot.
 27. Themethod of claim 18, wherein displaying the pressure distributionincludes a plurality of pressure points, wherein the spacing of thepressure points demonstrates the performance of the prosthetic foot. 28.A method of comparing the performance of prosthetic feet, comprising:obtaining a pressure distribution of a first prosthetic foot, saidpressure distribution defining a first trajectory; obtaining a pressuredistribution of a second prosthetic foot, said pressure distributiondefining a second trajectory; comparing said first trajectory with saidsecond trajectory; and determining which of said first and secondprosthetic feet has a superior performance based on said comparison. 29.The method of claim 28, wherein said comparison of said first and secondtrajectories includes comparing the smoothness of said trajectories. 30.The method of claim 28, wherein said first and second trajectoriescomprise a plurality of pressure points, and wherein said comparison ofsaid first and second trajectories includes comparing the frequency ofsaid pressure points.
 31. The method of claim 28, wherein said first andsecond trajectories comprise a plurality of pressure points, and whereinsaid comparison of said first and second trajectories includes comparingthe spacing of said pressure points.
 32. A method of comparing theperformance of a prosthetic foot and a human foot, comprising: obtaininga pressure distribution of a human foot, said pressure distributiondefining a first trajectory; obtaining a pressure distribution of aprosthetic foot, said pressure distribution defining a secondtrajectory; comparing said first trajectory with said second trajectory;and determining a performance rating for the prosthetic foot based onsaid comparison.
 33. The method of claim 32, wherein said comparison ofsaid first and second trajectories includes comparing the smoothness ofsaid trajectories.
 34. The method of claim 32, wherein said first andsecond trajectories comprise a plurality of pressure points, and whereinsaid comparison of said first and second trajectories includes comparingthe frequency of said pressure points.
 35. The method of claim 32,wherein said first and second trajectories comprise a plurality ofpressure points, and wherein said comparison of said first and secondtrajectories includes comparing the spacing of said pressure points. 36.A method of operating a prosthetic foot, comprising: obtaining apressure distribution of a prosthetic foot; determining whether thepressure distribution falls within a preselected range of rolloverperformance values for the prosthetic foot; and modifying the prostheticfoot to achieve a rollover performance within the range of preselectedrollover performance values.
 37. The method of claim 36, whereinmodifying the prosthetic foot comprises modifying a sole of theprosthetic foot.
 38. The method of claim 36, wherein the prosthetic footcomprises a foot cover and wherein modifying the prosthetic footcomprises modifying the foot cover.
 39. The method of claim 36, whereinmodifying the prosthetic foot comprises incorporating materials ofselected stiffness in the prosthetic foot.